Quantitation of low levels of IgM by electroimmunoassay.
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Electrophoresis, Agar Gel↗
Biomedical subjects
K M Rao
Publications and source records attributed to K M Rao.
Mutagenicity of N,N'-dimethylurea and methylamine hydrochloride in the Ames Salmonella/microsome test: absence of mutagenic response.
Methyl isocyanate (MIC) in aqueous solution forms methylamine (MA) and N,N'-dimethylurea (DMU). MA in buffered system further converts into its salt form, methylamine hydrochloride (MAH). Therefore, MAH and DMU were evaluated for their mutagenic activity in the in vitro Ames Salmonella/microsome mutagenicity test. The liquid preincubation protocol was followed, using tester strains TA98, TA100 and TA104 of Salmonella typhimurium, in the presence of 0, 5, 15 and 30% Aroclor 1254-induced rat liver S9 mixture. DMU and MAH did not induce a mutagenic response in any of the tester strains, both in the presence and in the absence of S9 mixture. The results therefore confirm that MIC in its native form or as its unknown metabolites is responsible for the mutagenic activity reported earlier by us in the his tester strains TA100 and TA104 of Salmonella typhimurium (Mutation Res., 204 (1988) 123-129) and not due to its hydrolysis products, MA or DMU.
Cyanates↗
Cytochalasins induce actin polymerization in human leukocytes.
We studied the effect of cytochalasins (B, D, and E) on the F-actin content in human neutrophils and lymphocytes using NBD-phallacidin labeling followed by flow cytometry. All three cytochalasins induced a concentration- and time-dependent increase in the F-actin content in both cell types. The order of potency was cytochalasin D greater than E greater than B. The increase in F-actin content was accompanied by a decrease in the G-actin content as measured by DNase I inhibition assay. These observations suggest that in intact cells cytochalasins may function differently compared to purified and semipurified systems, and their effects may be modified through other actin-binding or sequestering proteins. 2-deoxyglucose (20 mM) caused a decrease in the basal F-actin content and significantly reduced the change induced by the cytochalasins. These results suggest that the state of actin in intact cells is regulated by cytosolic ATP levels, primarily by the integrity of the glycolytic pathway. Based on these observations, we conclude that the mechanism of action of cytochalasins in intact cells is more complex than current models suggest.
Actin Cytoskeleton↗
Mutagenicity evaluation of riot control agent o-chlorobenzylidene malononitrile (CS) in the Ames Salmonella/microsome test.
o-Chlorobenzylidene malononitrile (CS), a riot control agent, was evaluated for its possible mutagenic activity in the Ames Salmonella/mammalian microsome mutagenicity test. Five histidine-deficient (His-) mutant tester strains of Salmonella typhimurium--TA97a, TA98, TA100, TA102 and TA104--were used. The liquid preincubation procedure was used with metabolic activation (presence of S9 mixture) and without metabolic activation (absence of S9 mixture). For the experiments with metabolic activation, three different concentrations of S9 fraction (supernatant of Aroclor 1254-induced rat liver homogenate at 9000 g)--5%, 15% and 30% in S9 mixture--were used. Along with mutagenic activity, CS was also evaluated for cytotoxic activity in all the five tester strains of Salmonella typhimurium, both in the presence and absence of S9 mixture. The mutagenic and cytotoxic activities of CS were assessed by counting the His+ revertant colonies and by counting the microcolonies (His-, auxotrophs in the background lawn), respectively, and the respective mean values were compared with the relative negative (solvent) control. A dose range of 12.5-800 micrograms plate-1 for CS did not induce a mutagenic response either in the presence or absence of S9 mix. No change in the negative mutagenic response of CS has been observed even in the presence of an elevated level of S9 fraction in the S9 mix. A dose of 200 micrograms plate-1 for CS was found to be cytotoxic by decreasing the surviving cells as well as His+ revertant colonies; however, the effect was reduced in the presence of an elevated level of S9 fraction in the S9 mix.
Animals↗
Flow cytometric analysis of nitric oxide production in human neutrophils using dichlorofluorescein diacetate in the presence of a calmodulin inhibitor.
Dichlorofluorescein (DCFH) oxidation assay measures hydrogen peroxide (H2O2), which is a derivative of superoxide anion. We found that a calmodulin antagonist, W-13, which is known to inhibit superoxide anion generation enhanced the capacity of human neutrophils to oxidize DCFH. To investigate this discrepancy we studied the role of nitric oxide (NO) in DCFH oxidation. Pure NO was capable of oxidizing DCFH, and the product formed had spectral properties identical to oxidized DCFH produced by H2O2. The arginine analog, NG-monomethyl-L-arginine (NMMA), which inhibits NO production, in combination with W-13 completely inhibited the stimulus-induced increase in DCFH oxidation. We conclude that the oxidation of DCFH in human neutrophils can occur by either H2O2 or NO.
Arginine↗
Continuous normothermic blood cardioplegia: simplified delivery circuit.
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Heart Arrest, Induced↗
Pentoxifylline modulates deformability, F-actin content, and superoxide anion production of polymorphonuclear leukocytes from diabetic cats.
Capillary occlusion is an early event in the development of diabetic retinopathy, and white blood cells have recently been shown to be involved. We have shown previously that pentoxifylline improves deformability and decreases F-actin content of unstimulated polymorphonuclear leukocytes from normal human subjects. The purpose of this study was to determine if pentoxifylline would improve three properties of unstimulated polymorphonuclear leukocytes from diabetic cats. The measured parameters were mechanical (whole cell deformability), structural (F-actin content) and biochemical (rate of superoxide anion production). Chronic hyperglycemia was induced in three cats by partial pancreatectomy, and they were kept in poor glycemic control for at least 6 months prior to the study. Polymorphonuclear leukocytes were isolated and the entry time of individual passive cells was measured during aspiration into a 4-micron micropipette under constant suction pressure (-15 cmH2O). Deformability was defined as the inverse of the entry time. F-actin content of passive cells was measured by NBD-phallacidin labeling followed by flow cytometry. The rate of superoxide anion production was measured spectrophotometrically by superoxide dismutase-inhibitable cytochrome c reduction. Following incubation for 15 min with 0.1, 1.0 and 10.0 mM pentoxifylline, the average entry time of passive polymorphonuclear leukocytes was reduced from control by 11 +/- 5% (P = 0.045), 17 +/- 6% (P = 0.007), and 36 +/- 5% (P < 0.001), respectively. The F-actin content decreased by 0%, 4 +/- 0.6% (P < 0.001), and 10 +/- 3% (P < 0.001), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
Actins↗
Age-related alterations in actin cytoskeleton and receptor expression in human leukocytes.
We studied a number of parameters, which may all depend upon cytoskeletal function, comparing lymphocytes and granulocytes (PMN) from young and old healthy donors. F-actin content was measured by NBD-phallacidin staining, followed by flow cytometry and was expressed as mean channel fluorescence (MCF). There were no differences in the basal F-actin content of PMN obtained from young (under 35 years old) and old donors (above 65 years). In contrast, the basal F-actin content was higher in lymphocytes obtained from the old donors (MCF, 56.8 +/- 2.9 vs 48.1 +/- 2.6 in the young; mean +/- SEM, n = 20, p less than .03). Stimulus-induced actin polymerization was slightly lower in the older age-group both in PMN and lymphocytes, but a significant difference was found only in PMN stimulated with the chemotactic peptide, N-formyl-methionyl-leucyl-phenylalanine (MCF 97.9 +/- 4.7 vs 88.6 +/- 3.4; young vs old, mean +/- SEM, n = 20, p less than .05). Interleukin-2 receptor expression was measured by staining with FITC-conjugated anti-CD25 antibodies and flow cytometry, following stimulation with phytohemagglutinin (PHA) or pokeweed mitogen (PWM). Perturbation of the cytoskeletal system with pentoxifylline, which has been shown to decrease F-actin content and inhibit the expression of several cell surface receptors, had similar effects on leukocytes from young and old donors.(ABSTRACT TRUNCATED AT 250 WORDS)
Actins↗
Comparative activity of three repellents against the ticks Rhipicephalus sanguineus and Argas persicus.
The residual repellent activity of N,N-diethylphenyl-acetamide (DEPA), N,N-diethyl-3-methyl benzamide (DEET) and dimethylphthalate (DMP) against the hard tick Rhipicephalus sanguineus (Latreille) and the soft tick Argas persicus (Oken) from topical application on rabbits and hens respectively in the laboratory have been studied. It was found that a 25% concentration of DEET gave strong repellency (greater than 90%) against larvae and nymphs of R. sanguineus for 15 and 7 days respectively and against A. persicus larvae and nymphs greater than 90% for 11 and 5 days respectively. Strong repellency (greater than 90%) against adults of the hard and soft ticks was observed for 9 and 7 days respectively with 40% DEET. DEPA at 25% concentration showed strong repellency (greater than 90%) against larvae and nymphs of R. sanguineus and A. persicus for 11 and 5 days respectively. Adults of hard and soft ticks were strongly repelled (greater than 90%) for 9 and 5 days respectively by 40% DEPA. DMP was found to be the least effective against all stages of both species of tick.
Acetamides↗
Changes in actin state and chemotactic peptide receptor expression in granulocytes during cytokine administration after autologous bone marrow transplantation.
We studied the changes in actin state and chemotactic peptide receptor expression in granulocytes from patients receiving different cytokines following high dose chemotherapy and autologous bone marrow transplantation (ABMT). The F-actin content in granulocytes was higher in all patients following ABMT. However, in patients receiving granulocyte colony-stimulating factor (G-CSF) and macrophage colony-stimulating factor (M-CSF) the increase in F-actin content was much greater than in those not receiving these cytokines (159, 149, and 90% for G-CSF, M-CSF, and noncytokine group, respectively). Patients receiving granulocyte-macrophage colony-stimulating factor (GM-CSF) had only a 62% increase in the F-actin content, which was not statistically significant from patients undergoing ABMT without any cytokines. Although the basal level of F-actin was high following ABMT, granulocytes from all patients showed an additional increase in F-actin content after stimulation with either the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (FMLP) or phorbol myristate acetate (PMA). The chemotactic peptide receptor expression was significantly higher in patients treated with ABMT alone or ABMT plus G-CSF. These observations suggest that the granulocytes generated following ABMT and cytokine administration may have different functional potential depending on the cytokine administered. Further studies to evaluate these potential differences are essential to devise optimal therapeutic protocols for maximizing the granulocyte protective function in this clinical setting.
Actins↗
Gas chromatographic detection of anaerobic bacteria from environment.
A rapid method of detection of anaerobic bacteria in environment using gas chromatograph is described. Metabolically produced volatile and non-volatile fatty acid by the anaerobic bacteria are detected gas-chromatographically. Using this technique anaerobic bacteria are detected from soil, air, laboratory and operation theatre environments and drinking water samples. In the polluted drinking water apart from drug resistant E. coli, Clostridium difficile is isolated indicating faecal pollution of drinking water from cases of antibiotic associated pseudomembraneous colitis. The method has great significance in detection of anaerobic bacteria in environment especially in the management of war wounds.
Bacteria, Anaerobic↗
Age-related studies of SIg, Leu-4 and concanavalin A receptor densities and capping in human lymphocytes.
We compared the cell surface antigen density and capping of three antigens in lymphocytes obtained from healthy, young (mean age 27 years) and elderly (mean age 76), population. There were no differences in the expression of surface immunoglobulin (SIg), concanavalin A (con A) receptors and Leu-4 antigen between the two groups. Kinetic analysis of these molecules revealed a slight decrease in capping in the older population, but the differences were not statistically significant. In order to test the possibility that subjecting the cells to metabolic stress might bring out the differences, we performed a kinetic analysis of SIg and con A capping in the presence of various concentrations of the metabolic inhibitor sodium azide. Although the capping in cells from elderly subjects was slightly more sensitive to azide, no statistical difference was found. Analysis of con A capping by a flow cytometric method yielded similar results, confirming the data obtained by visual capping experiments. We conclude that although a trend toward decreased capping was observed, there is little alteration in the surface molecule capping phenomenon in the age-groups studied.
Adult↗
Structure-activity relationship studies with mosquito repellent amides.
A series of amide analogues of N,N-diethyl-m-toluamide (DEET) and N,N-diethylphenylacetamide (DEPA) were synthesized to study their mosquito repellency in relation to chemical structure and physical properties. None of these parameters (vapor pressure, lipophilicity, and molecular length) could be related to protection time. However, when the protection time of all five amides derived from the same carboxylic acid was expressed in terms of all three parameters together, excellent correlation was obtained.
Acetamides↗
Pentoxifylline and other methyl xanthines inhibit interleukin-2 receptor expression in human lymphocytes.
Addition of pentoxifylline to lymphocytes caused a dose-dependent decrease in PHA-induced interleukin-2 receptor (IL-2R) expression. Expression of IL-2R protein and mRNA were inhibited by 60% at a concentration of 1 mM. Pentoxifylline also inhibited release of IL-2R into the medium by 85%. Treatment with recombinant IL-2 (50 U/ml) did not abrogate the effect of pentoxifylline. In addition to inhibition of IL-2R expression, pentoxifylline also decreased the expression of transferrin receptors and class I MHC antigens. Pentoxifylline also inhibited cell proliferation. However, aphidicolin, an inhibitor of DNA polymerase alpha inhibited cell proliferation to the same extent as pentoxifylline, but had no effect on IL-2R expression, indicating that inhibition of cell proliferation does not necessarily lead to inhibition of IL-2R expression. The inhibitory effect on IL-2R expression was also noted with other methylxanthines, theophylline and isobutylmethylxanthine, and with dbcAMP and forskolin. The inhibitory activity of pentoxifylline was prevented by W-13, a calmodulin antagonist, but not by HA-1004, a cyclic AMP-dependent protein kinase inhibitor. This suggests that pentoxifylline might act in part through a Ca2+/calmodulin-dependent mechanism. Pentoxifylline and other methylxanthines may prove useful in delineating the biochemical pathways involved in induction and expression of cell surface receptors.
1-Methyl-3-isobutylxanthine↗
N,N-diethylphenylacetamide in treated fabrics as a repellent against Aedes aegypti and Culex quinquefasciatus (Diptera: Culicidae).
The efficacy of fabrics impregnated with N,N-diethylphenylacetamide (DEPA), a new repellent, was studied in the laboratory and field against Aedes aegypti (L.) and Culex quinquefasciatus Say. DEPA-treated polyester cotton and cotton fabrics provided repellency for 30 and 36 d and had a half-life of 11 and 5 d, respectively. The repellent could not be applied at a rate of greater than 15% of fabric weight. DEPA-treated fabric patches were found to be a practical and novel approach and were effective for 90 d in the laboratory against Ae. aegypti and 77 d in the field against Cs. quinquefasciatus.
Acetamides↗
Insect repellent N,N-diethylphenylacetamide: an update.
N,N-diethylphenylacetamide (DEPA) has repellent activity against hematophagous insects including mosquitoes, black flies, horse flies, muscoid flies, rat fleas, and ticks, as well as land leeches and cockroaches. The efficacy of DEPA is comparable to that of N,N-diethyl-3-methylbenzamide (DEET) in both laboratory and field tests. Toxicological studies indicate that DEPA is safe for human use. Different formulations as well as fabrics impregnated with DEPA are effective for personal protection from insect bites.
Acetamides↗
Anti-inflammatory effects of pentoxifylline in claudication.
We measured neutrophil elastase/alpha 1 proteinase inhibitor complex (E/alpha) levels by ELISA in plasma samples drawn from 19 patients with claudication, before and at 1 and 2 months after initiation of pentoxifylline (PTF), 400 mg. p.o. tid. Plasma E/alpha levels declined in all eight patients whose initial values were more than 300 ng elastase per ml. Whole blood viscosity (wbv) was reduced by two months' treatment in 12 of 14 patients tested. The relative change in wbv was significantly related to the relative change in E/alpha (R2 = 0.8), for patients with elevated initial E/alpha levels, suggesting a common or related mechanism for the two effects. Plasma crosslinked fibrin D-dimer fragments (XDP) measured by ELISA as indicators of coagulation activity were lower compared to pretreatment levels in 9 of 10 samples drawn when symptoms were improved on PTF, whereas they were increased in 6 of 9 samples drawn when symptoms were worse or unchanged. Plasma viscosity, C-reactive protein and alpha 1-acid-glycoprotein did not change significantly with PTF treatment. Together these findings are consistent with the possibility that reduced microvascular neutrophil activation and coagulation play a role in the clinical efficacy of PTF in intermittent claudication.
Anti-Inflammatory Agents, Non-Steroidal↗
Control of the haematophagous fly Hippobosca maculata, a series pest of equines, by deltamethrin.
This study reports the results of both a small-scale and a large-scale field treatment to assess control of the haematophagous fly Hippobosca maculata Leach a serious pest of equines in a stud in India using a deltamethrin based formulation, Butox. In the small-scale field trial application of 2 litres of deltamethrin at 0.001-0.003% concentration gave 90-100% control over 30 days. At 0.004% and 0.005% concentrations complete control was recorded for 45 and 90 days respectively. Mass application of 2 litres of 0.005% deltamethrin to equines and bovines controlled infestations of H. maculata for 1 year.
Animals↗